The purpose of Bird
Families of the World is as an aid to world birders who
want to maximize their enjoyment of avian diversity by observing examples
of as many bird families as is reasonable within the time and money
available for travel, and as a study tool
for all interested readers. This project began in 1999. DNA evidence
has revised much of what was thought to be known about bird evolution
and relationships. It had been the 'wild wild West' for nearly two
decades as new research was published but, perhaps, a greater degree of
consensus is now being reached. While tracking proposed revisions to
the list of bird families, I've advocated for more consistency in the
use of evidence across bird families, at least within the passerines.

This
web project began on 9 Feb 1999 when I posted a short page on the
Dulidae [Palmchat]. While the list of Bird Families has been regularly
updated to accommodate new research through 14 editions, it was not
until 17 years and a month [6238 days] that, with the posting of the
Vireonidae [Vireos], the project finally has a web page with text and
photos for every family. Many of the old pages badly need updating in
both layout, text, and photos but at least the initial goal has been
reached. The updating of old pages — including the Dulidae — will go
on. I've used my own photos when I had them, but I'm very grateful to
the many photographers around the world who've permitted me to use
their wonderful shots when I needed them.
– D. Roberson, 9 Mar 2016

There
has been a trend towards higher numbers of Families in recent years —
welcomed by some, criticized by others — and that has played havoc with
longterm travel plans of (some) birders (like me). With recent
decisions by the AOU, IOC, Clements, and Winkler et al. (2015), I
finally accepted as a fait accompli the acceptance all the
New World nine-primaried passerine families first proposed in Barker et
al. (2013). This is with some reluctance, as I had hoped ornithologists
could reach some reasonable standard by which families could be
measured, perhaps something like a divergence date of 18-20 million
years ago (mya) or greater for passerine families (and older dates for
non-passerines). With these two splits, Puerto Rican Tanager [Nesospingidae], is split from the Spindalises, and Yellow-breasted Chat [Icteriidae],
moves from a New World warbler to nearer the Icterids, making it the
youngest family of all bird families at only about 11 mya. It also
creates a formal family name [Icteriidae] that will be confused with
that of the Orioles and allies [Icteridae].

Another new family is derived from Winkler et al. (2015) book on bird families: the Crested Jay Platylophus galericulatus of southeast Asia is remained and elevated to its own family Shrikejay [Platylophidae].
Recent genetic evidence suggested it is related to shrikes, not jays
but its true level of divergence from shrikes is not yet clearly
understood. Still, despite some uncertainty, Clements and IOC have
adopted the split.

The AOU added a family in their July 2018 supplement, the Royal-flycatchers [Onychorhynchidae],
following Ohlson et al. (2013). This group of six flycatchers in 3
genera are, along with Sharpbill, a sister taxa to all the rest of the
tyrant-flycatchers. The AOU elevates this family now, although a number
of world checklists are holding off until the results of a large
project currently underway is published. There will probably be other
families split off from the current Tyrannidae. I've also used the
sequence of families adopted by AOU for the New World suboscines.

The final new family was proposed by Cai et al. (2019), elevating the babbler genus Alcippe
from the Ground-Babbler family [Pellorneidae] on new genetic evidence.
All the members of the genus are currently called "fulvettas," but
there are other fulvettas in two other families, so this will cause
confusion. For the moment I'll call them the Alcippe Fulvettas [Alcippeidae]
but I hope taxonomists coin a better English names. When the
Pnoepygidae was proposed a decade ago for a genus of birds then-called
"wren-babblers," several authors (included me) suggested we adopt the
name Cupwings (a translations of the generic name) and most world lists
(e.g., Clements) do so. I'd like something better than "Alcippe
Fulvettas" for these mostly southeast Asian small babblers.

Finally,
I've adopted almost entirely the Clements/eBird sequence for the Bird
Families of the World, except that I follow the AOU sequence of
families in the New World suboscines.

Net result: + 5 families

The newest Bird Families
book [Winkler et al. 2015] has 243 families, and I now accept all of
those. My list in this edition has 258 families, 15 more than the Bird Families
book: Ground-Hornbills [also split by Clements, IOC], Old World Parrots
& Lories [Psittaculidae; also split by Clements, IOC, AOU, SACC],
Sharpbill [Oxyruncidae; split by SACC, Clements], Royal Flycatchers
[split by AOU], Butcherbirds [Cracticidae split from Artamidae
Woodswallows, adopted by Clements], Shrike-babblers and Silktails [both
splits recommended by Jønsson et al. (2016) on evidence of
ancient divergences], Erpornis, Bristle-flycatchers [Erythrocercidae;
also split by IOC], Hylias, Wallcreeper [Tichodromidae; also split by
Clements, IOC], Parrotbills & allies [Paradoxornithidae; also split
by Clements], Cinnamon Ibon, and the Alcippe Fulvettas. In short, this
Family list incorporates all of the extant families adopted by
Clements, AOU, or IOC [except Bananaquit, which is a tanager; Burns et
al. 2014].

My listing is of extant bird families. The Mohoidae, an endemic family from Hawaii that included 5 species in genus Moho and one in genus Chaetoptila
that had traditionally been considered honeyeaters in the Meliphagidae.
Genetic evidence proved they were not honeyeaters, but that they were
related to silky-flycatchers, waxwings, and other bombycillids. The Mohoidae is now extinct,
so it is not possible to search for any of its members. The last
remaining species was Kauai Oo, last proven alive in 1987, and now
considered extinct. Thus, when comparing number of families between
various list, it is important to use the list of extant families.
Clements states this number explicitly; IOC apparently does not.

Older essays, a long list of prior literature cited, and footnotes [now discontinued]
are found at the bottom of the 13th ed of this Checklist

I thank the editors of the Handbook
of the Birds of the World project; the late G. Stuart Keith,
co-author Birds of Africa series; the late James Clements,
author of the Clements' world checklists; Keith Barker, Frank Gill, Murray Lord,
Tom Schulenberg, and Van Remsen for sharing with me ideas and concepts about the
taxonomy and arrangement of a listing of bird families of the world. I
appreciate their input, but all the decisions reflected in the above
listing are mine, including all the errors.